CNSL is a versatile byproduct of cashew industries. The versatility of CNSL results from the multiple industrial applications for CNSL based products. Further, a large number of value added chemical products have been synthesized starting from chemical compounds isolated from CNSL.
With the increasing emphasis on reducing industrial emissions and release of effluents resulting from chemical reactions, use of catalysts is increasingly in vogue. With a view to improve the efficiency of reaction and the productivity, various types of catalysts which are industry friendly are being evaluated and industrially made use of.
There are different types of catalysts. Noble & precious metals are well known to be used as catalysts. There are heterogeneous & homogeneous catalysts as well as electro catalysts & organo catalysts. Latest cross linking catalysts, in which two or more adjacent molecules join to form a bigger molecule such as cross linked polymer, are presently recognized as highly active and economically suitable as well as effective for industrial applications.
U.S. Pat. No. 6,552,107 discloses synthesis of dopant involving sulfonation of methyl ether of 3-pentadecyl phenol. Processes for preparation of methyl ether of hydrogenated 3-pentadecyl phenol using KOH/water, alcohol & dimethyl sulphate in alcohol and sulfonation of 3-pentadecyl phenol using 98% c. H2SO4 at 70-80° C. are described in this document.
US2002035215 titled “Alkylated aryl disulfonic acid catalysts for crosslinking polyethylene” discloses a highly active condensation catalyst suitable for the crosslinking of alkoxysilanyl polyolefins. The crosslinked polymeric compositions obtained as described herein are indicated for use as coatings for electrical cables and wires.
U.S. Pat. No. 2,324,300 describes sulfonation of phenols and phenolic ethers of CNSL, cardanol, urushiol, and several alkyl ethers of these phenols where preferably the alkyl group is C1-C5 carbon atoms and the preferred ethers include primary, secondary and tertiary alkyl ethers of the above named phenols. The products disclosed are described to be useful in the wetting and detergency of textiles.
US2007154730 titled “Method of cross-linking a filled polymer based on polyethylene” describes a method of cross-linking a composition comprising firstly a polyethylene-based silane-grafted polymer, and secondly a filler.
US2008/0097038 deals with a silane-crosslinkable polymer composition comprising (i) at least one silane-crosslinkable polymer, and (ii) a catalytic amount of at least one polysubstituted aromatic sulfonic acid of a disclosed formula of composition. The polymer is used in the form of a wire or cable insulation coating.
Crosslinking in polyethylene and polypropylene is important to improve the properties such as heat deformation resistance, chemical resistance, stress cracking, shrinkage, etc. There are different techniques viz; radical crosslinking initiated by peroxide and irradiation. These techniques have its disadvantages. Incorporation of vinyl silane during polymerization has several advantages compared to grafting technique.